Havana, Cuba (CNN) -- The United States is out to destabilize Cuba, President Raul Castro charged Sunday in an address to the National Assembly.

The accusation comes on the heels of the island nation's recent detention of an American who is said to have distributed communications equipment to Cuban dissidents.

"The U.S. government has not renounced its goal of destroying the revolution," Castro said. "The enemy is as active as always. Proof of that is the detention, in the last few days, of an American citizen."

The U.S. State Department announced the detention a week ago, but declined to provide details.

"I don't want to comment on any of the details as to what he may or may not have been doing, simply because we don't want to -- we don't want to cause any harm, frankly," said State Department spokesman Ian Kelly.

The detained American is a subcontractor for Maryland-based Development Alternatives Inc., an economic development organization, the company's chief said. The man, who hasn't been publicly identified, was arrested by Cuban officials on December 5.

The American was involved in a new USAID program aimed at helping the U.S. government "implement activities in support of the rule of law and human rights, political competition, and consensus building, and to strengthen civil society in support of just and democratic governance in Cuba," DAI President and CEO Jim Boomgard said a week after the arrest.

DAI was awarded the USAID contract, called the Cuba Democracy and Contingency Planning Program, in 2008.

The U.S. Interests Section in Havana has requested to meet with the American as soon as possible, the State Department said in a statement. As of Sunday, U.S. officials said they haven't been granted access.